I hear you. It felt like it wouldn't go in for me but it does. Just keep trying. Did you removed the cross brace? It'll give you a little more clearance, I did it.

Yes, it does fit! Just barely--Whew! Agreed, what a puzzle!
No I didn't remove the cross brace, but I did remove the heat shield. I inserted the arm from the bottom, up into the cabin through the hole and rotated. The trick was getting it in the proper orientation above the drive shaft.
Hint for those installing: once you remove the old arm, try re-installing the old arm and notice every motion it takes to re-install. This will help with the "puzzle" motions required for the new one.

Now she shifts smooth and fast! Love the SSK!
Thanks to all for your DIY info!